资源环境科技发展态势分析平台

The characteristics of lightning corona sheath are of common concern in the lightning physics and lightning protection research. Using the spectra of two natural cloud-to-ground lightning including multiple return strokes recorded by a slit-less spectrograph, we investigated the electrical conductivity distribution along the radial direction of the channel. The results indicated that a high conductivity of above 10⁴ S/m existed within an average radius of around 1.8 cm and corresponded to the temperature of around 20,000 K. This finding reflects the characteristics of the current-carrying channel. The electrical conductivity decayed steeply to about 500 S/m with increasing radius and then decayed slowly. Based on these results, it was estimated that the corona sheath radii of the return stroke channel were around 3.34–19.10 cm. The corona sheath radius was positively correlated with the leader charge quantity and the apparent diameter of the corresponding leader channel. A wide corona-channel radius corresponds to an intense discharge.